HYBRIDIZATION HISTOCHEMICAL-LOCALIZATION OF 11-BETA-HYDROXYSTEROID DEHYDROGENASE TYPE-2 IN RAT-BRAIN

11 beta-hydroxysteroid dehydrogenase (11-HSD) activity allows aldoster one occupancy of mineralocorticoid receptors by inactivating endogenou s glucocorticoids. The expression of the 11-HSD2 gene, a low K-m, NAD( +) dependent species of 11-HSD, was found in several discrete areas of the rat brain by in situ hybridization. Cells strongly positive for 1 1-HSD2 mRNA were found in the commissural portion of the nucleus tract us solitarius, subcommissural organ and ventrolateral ventromedial hyp othalamus. Scattered labeled cells were also seen in the medial vestib ular nucleus. The expression of 11-HSD2 mRNA in the brain is quite dis tinct from that of 11-HSD1 mRNA and allows for diverse roles in modula ting corticosteroid receptor involvement in control of salt appetite, blood pressure and the hypothalamo-pituitary-adrenal axis.